Tilt cab truck

ABSTRACT

The present disclosure relates to a tilt cab truck having unique cab suspension means and cab tilting means. The suspension includes a pair of front and a pair of rear suspension arms that interconnect the cab and the frame. Front air springs are interposed between the front arms and the frame. The rear arms are connected to the frame by releaseable latch mechanisms and rear air springs are interposed between the latch mechanisms and the cab. Power cylinders for tilting the cab are arranged parallel to the front arms and are connected to the frame and the cab.

BACKGROUND OF THE DISCLOSURE

This disclosure relates to improved cab suspension means and cab tiltingmeans for a tilt cab truck. The cab suspension isolates roadirregularities from the cab and, thereby, enhances driver comfort andreduces fatique. In an automobile, the suspension supporting the vehiclebody upon the wheels is designed to have a low spring rate for theprincipal purpose of providing maximum comfort to the driver andpassengers of the vehicle. In a truck, springs of high rate are selectedto support the vehicle load and such springs have limited ability toabsorb bumps and vibrations. Improvements in truck wheel suspensionshave been proposed to increase operator comfort. These constructionshave been only moderately successful because the truck suspension must,first of all, support a very substantial vehicle load.

In view of the state of the art, it is a principal object of thisdisclosure to present a means for supporting the cab of a tilt cab truckupon a chassis frame that will isolate from the cab vibrationsassociated with road irregularities.

BRIEF SUMMARY OF THE DISCLOSURE

The present disclosure relates to an improved means for supporting thecab of a tilt cab truck on a truck chassis frame.

According to the disclosed embodiment of this invention, the cabsuspension means includes a pair of forward suspension arms that havetheir ends pivotally connected to the cab and to the frame. An airspring and a hydraulic shock absorber is interposed between each of theforward suspension arms and the frame. A pair of rear suspension armshave their upper ends pivotally connected to the cab and their lowerends pivotally connected to latch mechanisms that are releaseablysecured to the frame. An air spring and a hydraulic shock absorber isinterposed between each of the latch mechanisms and the cab.

This suspension construction permits the cab to traverse a jounce andrebound path relative to the chassis frame and, thereby, isolate fromthe cab bumps and vibrations induced by the encounter of the vehiclewheels with road regularities.

A pneumatic pressure source is connected to each of the air springs. Aleveling valve associated with each of the front springs regulates theair pressure in those springs and a single leveling valve regulates thepressure of the two rear springs. The air pressure in the front and rearsprings is controlled in order to maintain the cab at a constant heightabove the frame.

A stabilizer bar extends transversely of the vehicle and interconnectsthe two front suspension arms near their pivotal connections with thecab. The stabilizer bar functions as an anti-roll device to preventtilting of the cab about a longitudinal roll axis.

Left and right power cylinders arranged parallel to the front suspensionarms interconnect the cab and the frame. A hydraulic pressure source andcontrol system is connected to the latch mechanisms and to the powercylinders. When it is activated, the latches are disengaged and thepower cylinders are pressurized. This produces a force which urges thecab upwardly and forwardly about a transverse tilt axis coinciding withthe pivotal connection between the front suspension arms and the cab.

The present invention, rather than merely providing simple rubber mountsor similar devices between the cab and the frame, provides a fullsuspension system to assure driver comfort by isolating road vibrationsand bumps from the cab.

BRIEF DESCRIPTION OF THE DRAWINGS

The many objects and advantages of a truck constructed in accordancewith this invention will become apparent upon consideration of thefollowing detailed discussion and the accompanying drawings, in which:

Fig. 1 is a side elevational view of a tilt cab truck embodying thepresent invention.

FIG. 2 is a sectional view taken along section line 2--2 of FIG. 1 of aportion of the front cab suspension.

FIG. 3 is a rear elevational view of the rear cab suspension.

FIG. 4 is a side elevational view showing the cab in a partially tiltedposition.

FIG. 5 is a perspective view in schematic form of the hydraulicmechanism for releasing the latch mechanisms and tilting the cab.

FIG. 6 is a diagrammatic view of the pneumatic system for regulating airpressure in the air springs.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, wherein the presently preferredembodiment of this invention is illustrated, FIG. 1 discloses a tilt cabtruck having a unique suspension for supporting the cab upon the truckframe. The truck of FIG. 1 includes a frame assembly 10 that issupported by a wheel suspension on road wheels 12. A truck cab 14accommodates a vehicle driver and is supported on the frame assembly 10by a cab suspension which will be described. The truck of FIG. 1 is ofthe cab-over-engine type and means are provided to tilt the cabforwardly to expose the engine for servicing as will also be described.

The cab 14 is of generally box shape. It is connected to left and rightframe side rails 16 and 18 by left and right front suspension arms 20and 22. The cab 14 includes left and right structural members 24 and 25which support left and right depending brackets 26 and 27. A tie rod 28extends between the brackets 26 and 27. Left and right pivot bushings 30and 31 are supported on the tie rod 28 adjacent the brackets 26 and 27.A stabilizer tube 32 encloses the tie rod 28 and has its ends pivotallysupported by the left and right bushings 30 and 31. The forward ends ofthe left and right suspension arms 20 and 22 are secured to the outerends of the stabilizer tube 32. With this structure, the bushings 30, 31provide a pivotal connection between the suspension arms 20, 22 and thedepending cab brackets 26, 27.

An upstanding bracket 34 is welded to the outside of the leftlongitudinal frame rail 16. The rearward end of the suspension arm 20 ispivotally connected to the bracket 34 by means of a resilient pivotbushing 36. In a similar manner, an upstanding bracket is welded to theright frame rail 18 and the right suspension arm 22 is pivotallyconnected to that bracket by a resilient pivot bushing.

Left and right air springs 38 and 39 are interposed between the left andright suspension arms 20 and 22 and the frame assembly 10. A bracket 40is welded to the outside of the left frame rail 16 and the lower end ofthe air spring 38 is mounted on the bracket 40. The upper end of thespring 38 is connected to the suspension arm 20. In a similar fashion abracket 42 is welded to the right frame rail 18 to provide a support forthe lower end of the right front air spring 39. The upper end of airspring 39 is connected to the right front suspension arm 22.

Left and right front telescopic shock absorbers 44 and 45 have theirlower ends connected to the left and right frame rails 16 and 18 andtheir upper ends pivotally connected to the suspension arms 20 and 22.The shock absorbers 44 and 45 are constructed similar to conventionalhydraulic automotive shock absorbers to dampen jounce and reboundmovement of the cab 14 relative to the frame 10. The shock absorbers 44and 45 contain internal jounce and rebound bumpers which limit extremevertical displacement of the cab 14.

Left and right hydraulic power cylinders 46 and 47 have their forwardends pivotally connected to the cab brackets 26 and 27 and theirrearward ends pivotally connected to the frame brackets 34. The powercylinders 46 and 47 are arranged parallel to the front suspension arms20 and 22. The cylinders 46 and 47 are connected to the dependingbrackets 26 and 27 and the frame brackets 34 by pivot means having axesthat are fixed with respect to the brackets. The power cylinders 46 and47 are constructed to be pressurized and, thereby, exert forces upon thecab 14 which will tilt it forwardly about the axis of the bushings 30and 31. The mechanism for controlling the power cylinders 46 and 47 isshown in FIG. 5 and will be described later.

Shrouds 50 depend from the left and right sides of the truck cab 14 topartially enclose the cab suspension structure. In FIGS. 1 and 4 theleft shroud 50 is shown removed to expose this structure.

The suspension for the rear portion of the cab 14 includes left andright suspension arms 48 and 49. Left and right support brackets 51 and52 are connected to the cab 14. The forward ends of the suspension arms48, 49 are pivotally connected to the brackets 51, 52 by means ofresilient pivot bushings such as bushing 53. The rearward ends of theleft and right rear suspension arms 48 and 49 are pivotally connected tosupport members 54 and 55 which form part of the latch mechanisms. Thesupport members 54 and 55 are secured to the left and right frame rails16 and 18 by means of left and right hydraulic actuators 57 and 58 thatcontrol latch hooks 60 and 61 releaseably secured to the support members54 and 55. The actuators 57 and 58 are mounted on brackets 62 and 63secured to the side rails 16 and 18 and operate in a manner as will bedescribed.

The suspension for the rear of the cab 14 includes left and right airsprings 65 and 66. The left spring 65 has its lower end supported on thesupport member 54 and its upper end connected to portion 64 of the cabbody structure. The air spring 66 is mounted on the right support member55 and has its upper end engaging the cab portion 67.

The rear suspension for the cab 14 is completed by left and righttelescopic shock absorbers 68 and 69. The shock absorbers 68 and 69 aregenerally of automotive suspension construction and have their upperends pivotally connected to the cab body portions 64 and 67 and theirlower ends connected to the support members 54 and 55. The shockabsorbers 68 and 69 are designed to dampen jounce and rebound movementof the cab 14 with respect to the frame 10. They include internal jounceand rebound bumpers which function to limit the vertical movement of thecab 14 relative to the frame 10.

An air pressure source and an air pressure regulating system forcontrolling the pressure in the front air springs 38, 39 and rear airsprings 65, 66 is provided as shown in FIG. 6. An air manifold 71 isconnected to a source of pressurized air such as the pressure tank ofthe truck's air brake system. An air line 72 is connected to themanifold 71 and to a pressure protection valve 73. Air line 74 extendsbetween the valve 73 and an air reservoir tank 75. A front airsuspension line 76 connects with a left front leveling valve 77 which iscoupled to the left front air spring 38 by conduit 78. The right airspring 39 is joined through a conduit 79 to a leveling valve 81. Theleveling valve 81 is in communication with the front air suspension line76. A rear air suspension line 82 joins the reservoir tank 75 to asingle rear leveling valve 83. Left and right air suspension lines 83and 84 and a T-Fitting 86 join the rear air suspension springs 65 and 66to the leveling valve 82. The operation of the air suspension system ofFIG. 6 will be described below.

FIG. 5 illustrates the power system for tilting the cab forwardly inorder to permit servicing of the engine. The principal components of themechanism are shown in their appropriate relative position. The frameside rails 16 and 18 are included in the figure for reference purposes.The hydraulic actuators 57 and 58 for the latch hooks 60 and 61 aremounted on brackets 62 and 63 on the outboard sides of the rails 16 and18 as shown in FIGS. 1 and 3.

A manual pump 88 having a control handle 89 is supported on the rightside rail 18. A return line 90 and a pressure line 91 are coupled toinput and output ports, respectively, of the pump 88. Pressure line 91is connected to a pressure chamber situated on one side of the pistonwithin the extendable power cylinder 47. The return line 90 is connectedto the chamber on the other side of that piston.

A T-fitting 92 provides a connection for pressure line 93 which extendsto the power cylinder 46. Line 93 is coupled to the pressure chamber onone side of the piston within the cylinder 46. A T-fitting 94 connectsreturn line 96 with return line 90 and the pump 88. Return line 96 isconnected to the chamber on the other side of the piston within thepower cylinder 46.

The actuators 57 and 58 are coupled to the pressure line 93 by means ofT-fittings 97 and 98.

OPERATION

During normal operation of the truck of FIG. 1, the cab 14 is maintainedat a constant height above the frame assembly 10 by inflating theforward air springs 38, 39 and the rear air springs 65, 66 to anappropriate pressure. Referring to FIG. 6, the air reservoir tank 75receives air pressure from a pressure source such as the vehicle's airbrake system. The protection valve 73 is provided to protect theintegrity of the air brake system in the unlikely event there is a leakin the air suspension system. The front leveling valves 77 and 81 arecoupled to the reservoir tank 75. These valves sense the spacing betweenthe front of the cab 14 and the frame assembly 10. They admit or exhaustair pressure from the front air springs 38 and 39 in an appropriateamount to maintain the cab 14 at a constant height above the frame 14when the load in the cab 14 changes. The air springs 38 and 39 have arubber sleeve or boot which defines an air chamber. The air springs 38,39 are expanded and contracted in accordance with changes in theirinternal air pressure. The leveling valves 77 and 81 may be locatedwithin the air springs 38 and 39 or separately therefrom.

The rear air springs 65 and 66 are expandable and contractable in theirheight in response to changes in their air pressure. The rear levelingvalve 82 is connected to the air pressure reservoir tank 75 and feedsair to, or bleeds air from, the springs 65 and 66 in accordance with thespacing which the valve senses between the cab 14 and the frame assembly10. The leveling valve 82 contains valve means which prevent the airsprings from being deflated below a certain desired minimum airpressure.

When the vehicle of FIG. 1 is being driven over an irregular road thecargo of the vehicle is supported on the frame 10 which, in turn, isresiliently supported on the wheels 12 by high rate stiff suspensionsprings. In order to provide the vehicle operator in the cab 14 withmaximum comfort the present cab suspension system is provided. The cab14 will move up and down relative to the frame 10 as permitted by thearticulation of the front suspension arms 20, 22 and the rear suspensionarms 48, 49. The front air springs 38, 39 and the rear air springs 65,66 have a relatively low spring rate whereby the jounce and vibration ofthe frame assembly 10 is effectively isolated from the cab 14. The airsprings 38, 39, 65 and 66 resiliently support the cab 14 and the frontshock absorbers 44, 45 and the rear shock absorbers 68, 69 dampen themovement of the cab 14. These shock absorbers contain internal jounceand rebound bumpers which limit the extent of up and down movement ofthe cab 14.

The disclosed arrangement of air springs and suspension arms permitsgreater jounce and rebound movement of the cab 14 relative to the frame10 at a substantially lower spring rate than previously known methodsfor mounting a cab body on a vehicle frame. Another distinctive featureof the cab suspension is the anti-roll stabilizer tube 32 which preventsexcessive roll of the cab 14 about a longitudinal roll axis when thevehicle is maneuvering around a corner.

It will be noted in the side elevational view (FIG. 1) that the frontsuspension arms 20, 22 are arranged at an angle to the horizontal thatis less than the angle between the rear arms 48, 49 and a horizontalplane. This difference in slope of the front and rear arms providesanti-squat and anti-lift forces during acceleration and braking of thevehicle of FIG. 1.

The engine for the vehicle of FIG. 1 is supported on the frame 10beneath the cab 14. When it is necessary to service the engine thehydraulic system of FIG. 5 is activated. The handle 89 for the pump 88is reciprocated to develop hydraulic pressure in the hydraulic pressurelines 91 and 93. As the hydraulic pressure develops, the latch actuators57 and 58 will be energized causing the latch hooks 60 and 61 to move toa disengaged position with respect to the support members 54 and 55. Asthe pressure continues to build up in the pressure lines 91 and 93, thecylinders 46 and 47 will be extended whereby the cab 14 will be tiltedfrom its normal riding position of FIG. 1 to the engine exposingposition of FIG. 4.

The tilting of the cab 14 will occur about the axis of the pivotbushings 30 and 31. The transverse stabilizer tube 32 will maintain theforward suspension arms 20 and 22 in fixed positions relative to eachother so that the pivot axis for the tilting of the cab 14 will bemaintained horizontal. It will be noted from FIG. 4 that the rearsuspension for the cab 14 is connected to the support members 54 and 55rather than directly to the frame 10 whereby release of the supportmembers by the latches 60 and 61 will permit the cab 14 to tiltforwardly without requiring the disconnecting of individual suspensioncomponents.

The power cylinders 46 and 47 are arranged parallel to the frontsuspension arms 20 and 22 to form a parallelogram linkage system whenthe cab 14 is in its normal positions of FIG. 1. The cab 14, therefore,is free to move in jounce and rebound without interferring with thearticulation of the arms 20 and 22. With this arrangement it is notnecessary to provide conventional lost motion connections at one of theends of the power cylinders 46 and 47.

In summary, the preferred embodiment of the present invention ischaracterized by a cab suspension which provides superior driver comfortand a cab tilting mechanism which is of simplified construction.

The foregoing description presents the presently preferred embodiment ofthis invention. Details of construction have been presented for purposesof illustration rather than limitation. Modifications and alterationswill occur to those skilled in the art that will come within the scopeand spirit of the following claims.

I claim:
 1. A tilt cab truck comprising a truck chassis frame, a truckcab and suspension means interconnecting said frame and said cab,saidsuspension means being constructed to accommodate jounce and reboundmovement of said cab relative to said frame, said suspension meansincluding a plurality of rigid suspension arms and pivot means pivotallyconnecting said arms to said frame and to said cab, pivot meansinterposed between said cab and said frame providing a transverse tiltaxis about which said cab may be angularly displaced relative to saidframe, means operatively interposed between said cab and said frameconstructed to exert a force tending to angularly displace said cababout said transverse tilt axis, spring means operatively interposedbetween said cab and said frame constructed to resiliently support saidcab on said frame.
 2. A tilt cab truck according to claim 1 andincluding:a support means and at least one of said suspension arms beingconnected to said support means, releaseable latch means connecting saidsupport means to said frame.
 3. A tilt cab truck comprising a truckchassis frame, a truck cab and suspension means interconnecting saidframe and said cab,said suspension means being constructed toaccommodate jounce and rebound movement of said cab relative to saidframe, a pair of suspension arms and first pivot means pivotallyconnecting said arms to said cab, a pair of support means and secondpivot means connecting said arms to said support means, releaseablelatch means connecting said support means to said frame, pivot meansoperatively interposed between said cab and said frame providing atransverse tilt axis about which said cab may be angularly displacedrelative to said frame, means operatively interposed between said caband said frame constructed to exert a force tending to angularlydisplace said cab about said transverse tilt axis, spring meansoperatively interposed between said cab and said frame constructed toresiliently support said cab on said frame.
 4. A tilt cab truckaccording to claim 3 and including:shock absorber means operativelyinterposed between said cab and said frame, said shock absorber meansbeing constructed to dampen movement of said cab relative to said frame.5. A tilt cab truck according to claim 3 and including:a plurality ofhydraulic telescopic shock absorbers operatively interposed between saidcab and said frame, said shock absorbers being constructed to dampenmovement of said cab relative to said frame.
 6. A tilt cab truckaccording to claim 3 and including:a plurality of hydraulic telescopicshock absorbers operatively interposed between said cab and said frame,said shock absorbers being constructed to dampen movement of said cabrelative to said frame, said shock absorbers including limit meansconstructed to resiliently limit the extent of jounce and reboundmovement of said cab with respect to said frame.
 7. A tilt cab truckaccording to claim 3 and including:said spring means including a pair ofsprings connected to said cab and said support means.
 8. A tilt cabtruck according to claim 3 and including:said suspension means includinga pair of shock absorbers connected to said cab and said support means,said shock absorbers being constructed to dampen movement of said cabrelative to said frame.
 9. A tilt cab truck according to claim 3 andincluding:said spring means including a pair of springs connected tosaid cab and said support means, a pair of shock absorbers connected tosaid cab and said support means, said shock absorbers being constructedto dampen movement of said cab relative to said frame.
 10. A tilt cabtruck comprising a truck chassis frame, a truck cab and suspension meansinterconnecting said frame and said cab,said suspension means beingconstructed to accommodate jounce and rebound movement of said cabrelative to said frame, said suspension means including a pair of rigidsuspension arms and pivot means pivotally connecting said arms to saidframe and to said cab, pivot means interposed between said cab and saidframe providing a transverse tilt axis about which said cab may beangularly displaced relative to said frame, power cylinder meansoperatively interposed between said cab and said frame constructed toexert a force tending to angularly displace said cab about saidtransverse tilt axis, spring means operatively interposed between saidcab and said frame constructed to resiliently support said cab on saidframe.
 11. A tilt cab truck according to claim 10 and including:saidpower cylinder means comprising at least one elongated power cylinderarranged parallel to one of said suspension arms.
 12. A tilt cab truckaccording to claim 10 and including:said power cylinder means comprisinga pair of elongated hydraulic power cylinders arranged parallel to saidpair of suspension arms.
 13. A tilt cab truck according to claim 10 andincluding:said power cylinder means comprising at least one elongatedpower cylinder arranged parallel to one of said suspension arms, pivotmeans connecting one end of said power cylinder to said cab providing afixed pivot axis relative to said cab and said power cylinder, pivotmeans connecting the other end of said power cylinder to said frameproviding a fixed pivot axis relative to said frame and said powercylinder.
 14. A tilt cab truck comprising a truck chassis frame, a truckcab and suspension means interconnecting said frame and said cab,saidsuspension means being constructed to accommodate jounce and reboundmovement of said cab relative to said frame, a pair of front suspensionarms and first pivot means pivotally connecting said front arms to saidframe and to said cab, a pair of rear suspension arms and second pivotmeans pivotally connecting said rear arms to said cab, a pair of supportmeans and third pivot means connecting said rear arms to said supportmeans, releaseable latch means connecting said support means to saidframe, pivot means interposed between said cab and said frame providinga transverse tilt axis about which said cab may be angularly displacedrelative to said frame, power cylinder means operatively interposedbetween said cab and said frame constructed to exert a force tending toangularly displace said cab about said transverse tilt axis, springmeans operatively interposed between said cab and said frame constructedto resiliently support said cab on said frame.
 15. A tilt cab truckaccording to claim 14 and including:said spring means including frontsprings operatively interposed between said front arms and said frame,said spring means including rear springs operatively interposed betweensaid cab and said support means.
 16. A tilt cab truck according to claim14 and including:said spring means including a plurality of air springs,a source of air pressure and means connecting said source to said airsprings, said just mentioned connecting means including at least oneleveling valve constructed to sense the spacing between said cab andsaid frame and to regulate the air pressure in said spring means inresponse to changes in said spacing whereby said cab is maintained at asubstantially constant height above said frame.
 17. A tilt cab truckaccording to claim 14 and including:an anti-roll stabilizer barinterconnecting said front suspension arms.
 18. A tilt cab truckaccording to claim 14 and including;said power cylinder means comprisingat least one elongated power cylinder arranged parallel to one of saidfront suspension arms.
 19. A tilt cab truck according to claim 14 andincluding:said power cylinder means comprising a pair of elongatedhydraulic power cylinders arranged parallel to said pair of frontsuspension arms.
 20. A tilt cab truck according to claim 14 andincluding:said power cylinder means comprising at least one elongatedpower cylinder arranged parallel to one of said front suspension arms,pivot means connecting one end of said power cylinder to said cabproviding a fixed pivot axis relative to said cab and said powercylinder, pivot means connecting the other end of said power cylinder tosaid frame providing a fixed pivot axis relative to said frame and saidpower cylinder.
 21. A tilt cab truck comprising a truck chassis framehaving a frame member, a truck cab having a cab member and suspensionmeans interconnecting said members,said suspension means beingconstructed to accommodate jounce and rebound movement of said cabrelative to said frame, said suspension means including a suspension armhaving one of its ends pivotally connected to a first support means andthe other of its ends pivotally connected to a second support means,releaseable latch means connecting said first support means to one ofsaid members, said second support means being rigidly connected to theother of said members, pivot means operatively interposed between saidcab and said frame providing a transverse tilt axis about which said cabmay be angularly displaced relative to said frame, means operativelyinterposed between said cab and said frame constructed to exert a forcetending to angularly displace said cab about said transverse tilt axis,spring means operatively interposed between said cab and said frameconstructed to resiliently support said cab on said frame.
 22. A tiltcab truck according to claim 21 and including:said spring meansincluding a spring connected to said first support means and said othermember.
 23. A tilt cab truck according to claim 22 and including:a shockabsorber connected to said first support means and said other member,said shock absorbers being constructed to dampen movement of said cabrelative to said frame.